Biotechnology Question Bank, Roller Bottle and Spinner Cultures, Micro Carrier Beads

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15. Differentiate between roller bottle and spinner cultures?

  • In roller bottles the cells adhere to the total curved surface area of the microcarrier beads, thereby markedly increasing the available space for growth. These tissue culture bottles can be used in specialized CO2 incubators with attachments that rotate the bottles along the long axis. After each complete rotation of the bottle, the entire cell monolayer has transiently been exposed to the medium. The volume of the medium need only be sufficient to provide a shallow covering over the monolayer.

  • Spinner Cultures- Spinner cultures are used for scaling up the production of suspension cells. They consist of a flat surface glass flask with a suspended central Teflon paddle that turns and agitates the medium when placed on a magnetic stirrer. Commercial versions incorporate one or more side arms for sampling and/ or decantation. The cells are not allowed to settle to the bottom of the flask and thus cell crowding occurs only at very high densities.

16. What is the use of microcarrier beads?

  • The microcarrier beads are used to increase the number of adherent cells per flask and are either dextran or glass based. They come in a range of densities and sizes. The beads are buoyant and therefore can be used with spinner culture flasks. The surface area available for cell growth on these beads in huge.

17. What functions are performed by LAF? How many types of LAFs are present?

A LAF hood (Laminar Air flow hood) perform two functions-

  • To protect the tissue culture from contamination by protecting it from the operator (i.e. Sterile environment)

  • To protect the operator from the tissue culture (in situation of potential infection risk)

Depending on the nature of the cells and organisms being handled three types of culture hoods are available:

  • Class I hoods give good protection to the operators and to a lesser degree, the cell culture.

  • Class II hoods offer protection to both the operator and the cell culture.

  • Class III hoods are used for work with highly pathogenic organisms.

18. What are the drawbacks of using primary cell cultures?

The drawbacks of primary cell culture are that they are time consuming and require use of line animals or fresh tissue. Also, there can be considerable variation from one preparation to another particularly if prepared by different people. These difficulties can be overcome by using secondary cell cultures.

19. Name the scale up methods used for (a) adherent cell cultures (b) suspension cultures.

  • The scale up methods includes roller bottles with micro carrier beads for adherent cell cultures and spinner flasks for suspension cultures.

20. What are the advantages of using established cell lines for research by the scientists?

The advantages of using established cell lines is that their growth characteristics, media requirements and responses to selected reagents are established and therefore convenient for the scientist to use.

Questions on Genomics

1. Which microorganism’s genome was first sequenced?

Haemophilus influenzae

2. What is the field of genomic dealing with the sequence structure of DNA called?

Structural genomics

3. What are cDNAs spots on a glass slide used for expression studies called?Microarray

4. What are linear DNA sequences or clones having overlapping sequences called?

Contigs

5. What do EST stands for?

Expressed Sequence Tags

6. Based on genomic studies, why do people say that different species and organisms had a common ancestor 100 million years ago?

  • The genome sequencing projects have revealed that the genomes of very different organisms e.g. mouse and man may be quite similar. 12% of the 18,000 worm genes encode proteins whose biological roles could be inferred from their sequence similarity to yeast genes and vice – versa i.e. almost a third of the 6000 yeast genes have functional equivalents in worm genes.

  • It is estimated that the difference between human and chimpanzee genomes is only 1 to 3%. These similarities suggest that neither genome has changed much since we shared a common ancestor 100 million years ago.

7. Differentiate between functional and structural genomics?

  • Functional genomics- this is a field of study which co-relates the structure and sequence of the genome to its function. In this field the information provided by structure genomics is used to study the function of genes or protein in a systematic manner.

  • Structural Genomics- In structural genomics, one studies the sequence-structure relationship of a genome. It represents an initial phase of genome analysis which involves creating high resolution genetic physical and transcript maps and ultimately sequencing the genome. Because of rapid advances in the field of proteomics the study of three dimension structure of all proteins has also become easier because of structural genomics.

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